1. Field of the Invention
The present invention relates to a mobile communication control method and system. More particularly, the present invention relates to a mobile communication control method and a system for determining whether location registration is to be performed when a mobile station requests location registration in a mobile communication network of a roaming destination, wherein subscriber data for the mobile station is registered in a home location register (HLR).
2. Description of the Related Art
In a mobile communication network, a home location register (HLR) and a service control apparatus (SCF: Service Control Function) are provided, wherein the home location register performs movement management and call origination/incoming management for mobile stations, and the service control apparatus controls additional services. Although the home location register (HLR) and the service control apparatus (SCF) are separated in this embodiment of the present invention, they may be physically integrated as long as the functions are logically separated.
The home location register (HLR) stores subscriber information. The subscriber information includes information for specifying mobile stations that receive a communication service in a mobile communication network (home network) corresponding to the home location register (HLR), information on basic contract communication services (for example, normal communication service) that the mobile stations can receive, and information (which is called trigger information hereinafter) necessary for launching additional services (answering service, for example) controlled by the service control apparatus (SCF). Each time when a service area where a mobile station resides is changed, the new location of the mobile station is registered in the home location register (HLR) based on a request (location registration request) from the mobile station.
At the time of location registration, subscriber data are transferred from the home location register (HLR) to a switch (MSC: Mobile Switch Center or VLR: Visitor Location Register) to which the mobile station is connected. Accordingly, when the switch receives an originating call of a mobile station or an incoming call for the mobile station, the switch performs connection control of the call by using the subscriber data, and provides an additional service for the subscriber by accessing the service control apparatus (SCF) on the basis of trigger information included in the subscriber data.
A roaming service is provided by a contract between the carrier that operates the home network in which subscriber data of the mobile station are registered and another carrier that operates another mobile communication network. By using the roaming service, a mobile station whose subscriber data are registered in a home location register in a mobile communication network can receive a communication service in another mobile communication network. In such roaming service, when a mobile station sends a location registration request to a switch in the other mobile communication network of a roaming destination, the location registration request is transferred from the switch to which the mobile station is connected to the home location register (HLR). Then, the home location register (HLR) that receives the location registration request sends subscriber data of the mobile station to the switch to which the mobile station is connected.
When the switch has a function for executing an additional service by accessing the service control apparatus (SCF) of the home network by using the trigger information, the switch that receives the subscriber data sends an acknowledgment for receiving the subscriber data to the home location register (HLR) of the home network. The home location register (HLR) that receives the acknowledgement of the subscriber data from a switch of another mobile communication network performs location registration of the mobile station that sends the location registration request. Accordingly, the mobile station connected to the switch of another mobile communication network can receive communication services including additional services controlled by the service control apparatus (SCF) of the home network.
On the other hand, when the switch of the other mobile network does not have the function for executing additional services by accessing the service control apparatus (SCF) of the home network, the switch transfers information (execution function unsupported response) to the home location register (HLR), wherein the information (execution function unsupported response) indicates that the switch does not have the function for executing the additional services. The home location register (HRL) that receives the execution function unsupported response sends a response of rejecting location registration to the switch in response to the location registration request from the switch. This response for rejecting the location registration is transferred to a mobile station connected to the switch, so that the mobile station cannot receive a communication service in the other mobile communication network.
The home location register (HLR) that receives the execution function unsupported response may send a response for accepting location registration to the switch and perform the location registration in response to the location registration request from the mobile station. In this case, the mobile station connected to the other mobile communication network cannot receive the additional service, but can receive the basic contract communication service while the mobile station resides in the other mobile communication network.
In addition, the home location register (HLR) that receives the execution unsupported response may send a response for accepting location registration and service information of call origination restriction to the switch as subscriber information, and performs location registration. In this case, the mobile station connected to the other mobile communication network can receive a communication service only for incoming calls.
As mentioned above, according to the conventional mobile communication control method based on a location registration request sent from the mobile station in the other mobile communication network, when the switch does not have the function for executing additional services by accessing the service control apparatus (SCF) of the home network, the switch rejects or accepts location registration, or accepts location registration only for a call origination restriction service, uniformly, irrespective of details and status of additional services that the subscriber subscribes to. Therefore, control of accept/reject for location registration cannot be performed for each subscriber based on details and status (activated and inactivated) of additional services to which the subscriber subscribes.